Fluid pump



Dec. 19, 1967 L TH 'ET'AL 3,358,609

FLUID PUMP 3 Sheets-Sheet 1 Filed Sept. 13, 1965 s RHPE E W S V265 TV- fw .c, M WM 2 Q m n (a w MIA I I m I M 0% a V. B

Dec. 19, 1967 R. WORTH ETAL 3,358,609

FLUID PUMP Filed Sept. 13, 1965 5 Sheets-Sheet 2 INVENTORS ZEW/S A. WORTH ua/m c. PAP/WEE l/EFOME mam/5e QJ MLJ MA 2 ATTORNEYS United States Patent 3,358,609 FLUID PUMP Lewis R. Worth, Deerfield, and John C. Parmer, Winnetka, Ill., and Jerome F. Parmer, Westover, W. Va., assignors to Cole-Farmer Instrument 8; Equipment Co., Chicago, 111., a corporation of Illinois Filed Sept. 13, 1965, Ser. No. 486,756 8 Claims. (Cl. 103-149) ABSTRACT OF THE DISCLOSURE A peristaltic pump is described which includes a housing with a fluid conducting tube having a portion disposed therein forming a loop. Rotary means disposed in the housing are supported by hearing means supported in the housing. The rotary means engage the tube to compress same and produce a peristaltic action therein. The housing is formed in identical halves having mating surfaces extending transversely of the axis of rotation of the rotary means.

This invention relates to fluid pumps and, more particularly, to a peristaltic pump of improved constructions.

There are a number of different types of peristaltic pumps, all of which operate to provide a moving region or moving regions of compression along the length of a compressible fluid conducting tube. The movement of the compressed region forces fluid ahead of it, and the action of the tube in returning to its uncompressed form provides a partial vacuum to cause fluid flow in behind the compressed area in the tube. In some such pumps, the tube extends in a straight line; however, in the pump of the present invention, the tube is enclosed in a housing and forms a loop therein. The particular form of peristaL tic pump within which the invention is concerned generally includes a rotating structure having at least one portion which engages the tube in a manner to provide the desired moving regions of compression. Peristaltic pumps have varied uses, and are especially applicable where it is desired to provide a measured fluid flow which is capable of close regulation, such as in certain laboratory applications.

Generally, peristaltic pumps which provide accurate flow rates, long 'life and reliability have tended to be relatively expensive. Such pumps have also often had a problem of the looped tu-be therein snaking around in the housing due to the longitudinal forces exerted thereon by the portion of the rotating structure which engages it. In addition, such pumps have sometimes encountered a problem in that the moving elements therein interfered with the fluid flow by engaging and pinching the tube.

It is an object of this invention to provide a peristaltic pump of improved construction and operation.

Another object of the invention is to provide a peristaltic pump which is low in costand reliable of operation.

Still another object of the invention is to provide a peristaltic pump which is simple to maintain and wherein parts may be replaced with relative case.

A still further object of the invention is to provide an improved peristaltic pump which is fully reversible in its operation.

Other objects, and the various advantages of the invention will become apparent to those skilled in the art from the following description taken in connection with the accompanying drawings wherein:

FIGURE 1 is an end view, with part broken away, of a peristaltic pump constructed in accordance with the invention;

FIGURE 2 is a sectional View taken along the line 2-2 of FIGURE 1;

FIGURE 3 is an exploded top view of the pump of FIGURES 1 and 2;

FIGURE 4 is an end view, with part broken away, of another embodiment of the invention;

FIGURE 5 is a sectional view taken along the line 5-5 of FIGURE 4;

FIGURE 6 is an exploded top view of the pump of FIGURES 4 and 5;

FIGURE 7 is an end view, with part broken away, of a still further embodiment of the invention;

FIGURE 8 is a sectional view taken along the line 8-8 of FIGURE 7; and

FIGURE 9 is an exploded top view of the pump of FIGURES 7 and 8.

In accordance with the invention, the peristaltic pump thereof comprises a housing with bearings supported therein. A portion of a fluid conducting tube is disposed in the housing and forms a loop. A rotary structure is disposed in the housing supported by the bearings and has at least two portions engageable with the tube to compress same and produce a peristaltic action therein. The rotary structure has an axis of rotation extending through the loop formed by the tube. The housing is formed in identical halves having mating surfaces lying in planes extending transversely of the axis of rotation.

Each of the halves of the pump housing may be provided with engaging portions on the mating surfaces which are adapted to align the halves in a predetermined relation. The looped portion of the tube may be disposed in a groove extending around the inner surface of the housing. When the rotary structure includes a plurality of rollers extending between a pair of axially aligned discs as shown in the drawings, the groove prevents engagement of the discs with the tube when the tube is compressed. Inlet and outlet holes are provided in the housing and the outlet hole may be directed to provide a bend in the tube which is generally opposite to the 'bend of the loop formed thereby to prevent longitudinal movement of the tube. The outer race of each of the bearings which support the rotary structure in the housing is shrunk fit into an opening in the housing.

Referring now more particularly to FIGURES 1-3, a peristaltic pump constructed in accordance with the invention is shown. The pump includes a housing 11 formed in identical halves 12 and 13. The housing is constructed of a transparent plastic, preferably an acrylic resin, such as Plexiglas. The interior of housing 11 has a pumping chamber 15 therein and is held together by bolts 17. The halves 12 and 13 of the housing separate along mating surfaces 21 and 22 and such surfaces contain projections 23 and 24 respectively, which fit into corresponding recesses 25 and 26 for aligning the halves 12 and 13 in a predetermined relation to each other. The projections 23 and 24 and the recesses 25 and 26 are in identical places on the respective halves 12 and 13 such that, as mentioned before, the halves are identical.

Fluid is conducted through the pump in a fluid conducting plastic tube 31. Tube 31 is deformable and has a memory, that is, it will return to its original shape after being deformed. As is well known in the art of peristaltic pumps, if a moving region or moving regions of compression are provided along the length of the tube 31, the action of the compressed regions pushing the fluid ahead and the action of the tube in returning to its original uncompressed shape provide a vacuum to cause fluid flow in the tube according to the direction of movement of the regions of compression. Tube 31 extends through an inlet hole 33 and forms a loop in the cavity 15 before extending outwardly of the housing through an outlet opening 34. The tube is positioned in housing 11 by means of an annular groove 35 formed in the interior wall of the housing. The axis of the left hand part of groove 35 (as viewed in FIGURE 1) corresponds to the axis of rotation of shaft 41, Whereas the axis of the right hand part is designated as point 36. The plane of surfaces 21 and 22 extends exactly through the middle of groove 35 such that the identical nature of the halves 12 and 13 is achieved.

In order to provide the moving area or areas of compression along the length of the compressible fluid couducting tube 31, a rotary structure 37 is disposed in the cavity 15. Rotary structure 37 includes a pair of axial- 1y spaced discs 38 and 39 mounted on a drive shaft 41. Drive shaft 41 is supported for rotation in housing 11 by means of metal ball bearings 43 and 45. A plurality of ball bearing supported rollers 47 extend between discs 33 and 39 and the axis of rotation of each of rollers 47 is parallel to and displaced from the axis of rotation of shaft 41.

Each of rollers 47 has an outer surface adapted to engage the tube 31 as the structure '37 rotates about the axis of shaft 41 in response to rotation of shaft 41 by suitable driving means, not shown. As may be noted from FIGURE 1, the axis of rotation of shaft 41 is displaced a distance to the left of the axis of the annular groove 35 (indicated in FIGURE 1 as point 36). Accordingly, when a roller is in the left hand portion of the cavity 15, as viewed in FIGURE 1, it will operate to compress the tube. 31 against the housing 11 and flatten the tube out as shown in cross section in the upper part of FIGURE 2. This forces fluid ahead of the compressed region. When'the tube 31 returns to its normal shape once the roller 47' has passed by, a vacuum will be produced in the tube tending to draw fluid therethrough in the desired direction. 7

The bearings 43 and 45 are secured in the respective halves 12 and 13 of housing 11 in a manner which is simple and which affords reliable and sturdy construction. Halves 12 and 13 are provided with openings 51 and 52 therein, respectively. A slightly wider opening is provided in each of halves 12 and 13 between the respective openings 51 and 52 and the chamber 15. These slightly wider openings are designated as 53 and 54 respectively. Openings 53 and 54 are each of a diameter which is equal to or less than the outer diameter of the outer race of antifriction bearings 43 and 45. The housing 11 is'heated to cause expansion of openings 53 and 54 to a diameter which will accommodate the outer races of the respective bearings 43 and 45. Bearings 43 and 45 are then positioned in the openings 53'and 54 and the housing 11 is permitted to cool whereby the opening in which the hearing is disposed shrinks to the given diameter and secures the bearing in the housing. Theshrinkfit thus provided secures the metal bearing in the plastic housing without the need for additional structural elements such as screws, brackets, etc. Thisreduces production time and costs and greatly simplifies the product:

A number of other advantages accure from the invention. The construction of; the housing 11, identical halves separable along surfaces lying in planes transverse to the axis of shaft 41, lowers production costs in that each half of the pump housing is made in the same production operation. This type of construction also facilitates the stocking of replacement parts, and its simplicity affords sturdy construction and reliability. The transparent. nature ofthe housing provides an attra'ctiveand saleable product and permits a user ofthe equipment to observe the condition of the tube 31. Where the tube is transparent,- fluid flow may also beobserved. The groove 35 spaces the tube 31 from the discs 38 and 39m eliminatethe-dang'er of tube pinching. The groove 35 and the loopoftube 31.

therein are symmetrical on either. side of'a plane throughthe axis of rotation of structure 37, thereby permitting r tation of the rotary structure 37 in either direction for effecting immediate reversal of fluid flow. Such a feature enables a single pump to be utilized, for example, to both fill and empty a tank of'liquid ohernicals.

Because of the rotation of rotating structure 37, and despite the fact that rollers 47 are free to roll on the surface of tube 31, and do so due to frictional forces, forces are still applied to tube 31 which may have a tendency to cause the tube to snake or slide around longitudinally in groove 35. In the pump of the invention, such an undesirable occurrence is prevented by making openings 33 and 34 of substantially the same outer diameter as the tube 31 and by disposing openings, 33 and 34 such that tube 31 is bent opposite to the bend of the loop which tube 31 forms in chamber 15-. Tube 31 is deformable due to its flexible nature and, when structure 37 is rotated counterclockwise (as viewed in FIGURE 1), any tendency for structure 37 to force tube 31 through opening 34 is prevented by the corner 57 at the edge of opening 34 which will engage the tube 31 and cause the tube to deform and provide a small bulge 59. This bulge prevents tube 31 from being urged through opening 34. A similar bulge occurs at opening 33 when the rotation of structure 37 is reversed.

When the length of tube 31 within housing 11 becomes worn due to the frictional forces of the rollers 47 passing thereover, it is possible to easily provide a new portion of tube 31 in chamber 15 by grasping the outlet end of' tube 31 and pulling thereon. The pulling force will stretch the tube 31 and eliminate the bulge 59 at corner 57. By exerting a further pull on the tube 31, the tube may then be drawn by hand through housing 11 until the desired unwornlength of tube 31 is inside the housing. If this operation is performed before the worn portion ofthe tube ruptures, the fact that the tube is worn on its outer surface will not impair its ability to conduct fluid as required. Thus, the tube need not be replaced. I

Referring now to FIGURES 4, 5 and a further em;- bodirnent of the invention is shown. The tuition" lif= ferences in this embodiment over the embodiment livVrl in FIGURES l-3, is in the form of the loop in the fluid conducting tube and in the configuration and operation,

of the rotating structure in the housing which engages.

the tube. In the embodiment. of FIGURES 4, 5' and 6,

the pump comprises a housing 111 having identical halves 112, and 113. As was previously. the case, housing ll-l is constructed of transparent plastic, preferably an acrylic resin. The two halves of housing 111 are held together by bolts 117 and a pump cavity 115 is formed in housing 111. The parting or mating surfaces 121 and 122 are posi tioned such that each half 112 and 113 is identicahaud are of a configuration which prperly aligns the halves when the surfaces mate. A flexible tube; 131 extends'intoavity 115 through. an opening 133 in housing 111. Tabs 131 forms a helical loop in cavity 115' and passes through; an outlet opening 134 at the same level as opening 133' and on the opposite side of housing'lii. The looped per: tion. of tube 131 is disposed in a groove 135' which is also helical in shape and is formed in. the inneirwalfl of" housing 111. Groove 135maii1tains-the tube 131-spaced from the rotary structure 137. The of'theupperl part of groove (as viewed in FIGURE 4) is; the same as the axis .of shaft 141. The axis of the, lower part orgroove 135 is designated as point'136'. The upper and; lower-parts of groove 135 are joined by a flatcorresponding tothe distance between theaxis of shaft*14'1- andaxis 136; The

axis of the lower part of groove-135, designated as-point 136in FIGURE 4', is displaced from the axis of shaft 141 of the rotary structure 137. This allows expansion oftube' 131 just prior to its-entry into openings 133 and-134. The

displacement is selected such that this expansion is only partial, creating a nozzleeflfectatthe outlet ofthe pump" to maintain pressure in the section of tube 131 inside cavity 115.

The rotary structure 137 operates as did the rotary structure 37 in the previously discussed embodiment to provide the moving area or areas of compression along the length of the compressible fluid conducting tube 131:

Rotary structure 137 includes a pair of axially aligned discs 138 and 139 supported on a drive shaft 141. Drive shaft 141 is supported for rotation in ball bearings 143 and 145. Ball bearings 143 and 145 are supported in the respective halves 112 and 113 of housing 111 in the same manner as ball bearings 43 and 45 of the previously described embodiment were supported in halves 12 and 13. Rotary structure 137 further includes a plurality of rollers 147 ball bearing supported between discs 138 and 139 for rotation about axes which are parallel to the axis of rotation of shaft 141. Because of the 360 tube wrap and the nozzle effect previously described, pulsations are minimized and accurate metering of the fluid being pumped is possible.

In the previously discussed embodiment, the frictional force between the tube 31 and the rollers 47 causes rollers 47 to rotate as the structure 37 rotates. Under some circumstances, it may be desirable to reduce wear on the fluid conducting tube and avoid snaking caused by the rollers and, accordingly, in the present embodiment, the rollers 147 are positively driven. To achieve this, a planetary gear arrangement is provided including a plurality of planet gears 148 each drivingly attached through disc 138 to a respective roller 147. Planet gears 148 engage an annular gear 149 at one end of cavity 115 and which is molded as an integral part of housing half 112. The annular gear 149, as an alternative, may be made separately and press fit into housing half 112. As shaft 141 rotates rotary structure 137 about its axis, the annular gear 149 rotates each of planet gears 148 to drive rollers 147 at the desired rate.

In the case where gear 149 is molded as an integral part of the housing, and where each of the housing halves 112 and 113 are made identical, a corresponding annular gear 151 is provided in housing ha'lf 113 and serves no purpose when the pump is in the configuration shown in FIGURES 4-6. In the event of wear or damage to annular gear 149, the attitude of rotary structure 137 with respect to housing 111 may be reversed such that the planet gears 148 mesh with gear 151. Thus, a replacement part is unnecessary. As was the case in the previous embodiment, the construction is symmetrical for easy reversal.

Referring now to FIGURES 7, 8, and 9, a still further embodiment of the invention is shown. In this embodiment, the fluid conducting tube is formed in a helical loop in the pump housing, as was the case in the embodiment of FIGURES 4-6, but the rotary structure is more similar to that utilized in the embodiment of FIGURES 1-3. The embodiment of FIGURES 7-9 includes a housing 211 which is constructed of clear plastic, preferably an acrylic resin. The housing is formed in identical halves 212 and 213 and defines a cavity 215. The halves 212 and 213 are held together by bolts 217.

A flexible plastic fluid conducting tube 231 enters the cavity 215 in housing 211 through an inlet opening 233, forms a helical loop therein, and exits through outlet opening 234. A helical groove 235, formed in the inner wall of housing 211, holds and guides the looped portion of tube 231 in the desired helical configuration. The axis of groove 235 (point 236 in FIGURE 7) is displaced from the axis of shaft 241 as was the case in the previously describe embodiments. Surfaces 221 and 222 extend transversely of the axis of shaft 241, the axis of the groove 235 and the axis of the loop in tube 231.

The halves 212 and 213 separate along mating surfaces 221 and 222 which are positioned such that each half is identical. Surfaces 221 and 222 are of a configuration to align the two halves 212 and 213 with respect to each other. As was the case in the previous two embodiments, the pump is symmetrical, enabling reversal.

Rotary structure 237 is comprised of ball bearing supported rollers 247 extending between axially aligned discs 238 and 239. Discs 238 and 239 are secured to a drive shaft 241 which is supported for rotation in ball bearings 243 and 245. Ball bearings 243 and 245 are secured in the respective halves 212 and 213 of housing 211 in the same manner as the ball bearings of the previous embodiments were secured in their housings. It will be noted from FIGURE 8 that the groove 235 is spaced a sufficient distance from the discs 238 and 239 such that the discs will not pinch the tube 231. The advantages accruing from the device of the FIGURES 7-9 are similar to those found in the previous embodiments.

It will therefore be seen that the present invention provides an improved peristaltic pump which is low in cost and reliable of operation. The pump is easy to maintain and replacement of parts is facilitated by the simple construction. The pumps are capable of maintaining uniform fluid flow despite variation in pressure because of their positive displacement pumping. For example, pumps have been constructed in accordance with the invention which are capable of delivering 0.9 quart per minute at 600 rpm. and maintain such delivery at a relatively constant level from 0 to about p.s.i. above atmospheric pressure. Various modifications and embodiments of the invention, other than those shown and described herein, will be apparent to those skilled in the art from this description and accompanying drawings. Such other modifications and embodiments, as well as those shown and described herein, are intended to fall within the scope of the appendant claims.

We claim:

1. A peristaltic pump comprising a housing having hearing means supported therein, said housing having a groove therein extending around the inner surface thereof, a fluid conducting tube positioned in said groove in said housing forming a loop, a rotary structure including a pair of axially spaced support members positioned on opposite sides of said groove, each support member being supported for rotation on said bearing means in said housing, said rotary structure including a plurality of rollers extending between said support members and engageable with said tube to compress same and produce a peristaltic action therein in response to rotation of saidsupport members, said support members having their outer peripheries adjacent the outer peripheries of said rollers, said groove being of sufiicient width and depth to accommodate said tube upon compression thereof and being spaced from said support members an amount suthcient to prevent engagement of said support members with said tube upon compression thereof.

2. A peristaltic pump comprising a housing having hearing means supported therein, said housing having a groove therein extending around the inner surface thereof and further having inlet and outlet holes therein communicating with said groove, a fluid conducting tube having a portion disposed in said groove in said housing forming a loop, said tube extending through said inlet and outlet holes and being radially deformable and having, when not deformed, an outer diameter substantially equal to the diameter of said outlet hole, said outlet hole being directed to provide a bend in said tube which is generally opposite to the bend of the loop formed thereby such that longitudinal force exerted on said tube to urge same toward said outlet hole will cause said tube to deform at said outlet hole and prevent longitudinal movement of said tube, said deformity constituting the only resistance to longitudinal movement of said tube so that said tube may be pulled through said housing, and rotary means disposed in said housing and supported by said bearing means, said rotary means being engageable with said tube to compress same and produce a peristaltic action therein.

3. The combination of claim 2 wherein said housing is comprised of a transparent plastic and is provided with a pair of mutually aligned openings therein, and wherein said bearing means comprise a pair of anti-fraction bearings, each having an outer race which is shrunk fit into a respective one of said openings.

4. A peristaltic pump comprising a housing having bearing means supported therein, a fluid conducting tube havingv a portion disposed in. said housing and forming a loop, rotary means disposed in said housing and supported by said bearing means, said rotary means having at least two portions engageable with said tube to compress same and produce a peristaltic action therein, said rotary means having an axis of rotation extending through the loop formed by said tube and including a planet gear for rotatably driving said one portion, said housing enclosing a first annular gear secured thereto and engaging said planet gear for driving the same in response to rotation of saidrotary means about said axis thereof, said housing enclosing-a second annular gear secured thereto, said housing being formed in identical halves having mating surfaces lying in planes extending transversely of said axis of rotation between said first and second annular gears,

whereby the disposition of said rotary means with respect to said housing may be reversed when said first annular gear becomes worn such that said second annular gear engages said planet gear for driving same in response to rotation of said rotary means.

5.. A peristaltic pump comprising a housing having hearing means supported therein, said housing further having a spiral grooveextending around the inner surface thereof, a fluid conducting tube having a portion disposed in said groove in said housing form a spiral loop, and rotary means disposed in said housing and supported by said bearing means, said rotary means being engageable with said tube to compress same and produce a peristaltic action therein, said rotary means having an axis of rotation. extending through the loop formed by said tube, said housing being formed in identical halves, each half having an irregular mating surface extending transversely of said axis of rotation, said housing being divided on planes extending through said spiral groove such that the portions of said spiral groove in said identical halves are identical, said irregular mating surfaces being identical and being shaped: to accurately position said halves with respect to each other.

6'. The combination of claim wherein said groove in said housing and said portion of said tube in said housing are symmetrical on either side of a plane passing through said axis of rotation.

7. Aperistaltic pump comprising a housing. having hearing means supported therein, said housing further having a generally helical groove extending around the innersurface thereof and having inlet and outlet openings, a fluid. conducting tube passing throughsaid inlet and outlet openings and having a portion disposed in said groove in said housing to form a generally helical 360 loop, and rotary means disposed in said housing and supported by said bearing means, said rotary means being engageable with said tube to compress same and produce a peristaltic action therein, said rotary means having an axis of rotation extending through the loop formed by said tube, said groove being shaped with respect to the axis of rotation of said rotary means to allow only partial expansion of tube just prior to its entering said outlet opening and create a nozzle elfect to minimize pulsations. i

8. The combination of claim 7 wherein said groove has a first part with a first axiscorresponding to the axisof rotation of said rotary means, said groove having .a second part adjacent said outlet opening, said second part having a second axis parallel with and displaced from said first axis whereby said groove defines an eccentric path for the 360 loop portion of said tube, said second axis being displaced from said first axis a distance such that said rotary means only partially relieves the compression on said tube adjacent said outlet opening to provide the nozzle effect.

References Cited UNITED STATES PATENTS DONLEY J. STOCKING, Primary Examiner.

WILBUR J. GOODLIN, Examiner. 

1. A PERISTALTIC PUMP COMPRISING A HOUSING HAVING BEARING MEANS SUPPORTED THEREIN, SAID HOUSING HAVING A GROOVE THEREIN EXTENDING AROUND THE INNER SURFACE THEREOF, A FLUID CONDUCTING TUBE POSITIONED IN SAID GROOVE IN SAID HOUSING FORMING A LOOP, A ROTARY STRUCTURE INCLUDING A PAIR OF AXIALLY SPACED SUPPORT MEMBERS POSITIONED ON OPPOSITE SIDES OF SAID GROOVE, EACH SUPPORT MEMBER BEING SUPPORTED FOR ROTATION ON SAID BEARING MEANS IN SAID HOUSING SAID ROTARY STRUCTURE INCLUDING A PLURALITY OF ROLLERS EXTENDING BETWEEN SAID SUPPORT MEMBERS AND ENGAGEABLE WITH SAID TUBE TO COMPRESS SAME AND PRODUCE A PERISTALTIC ACTION THEREIN IN RESPONSE TO ROTATION OF SAID SUPPORT MEMBERS, SAID SUPPORT MEMBERS HAVING THEIR OUTER PERIPHERIES ADJACENT THE OUTER PERIPHERIES OF SAID ROLLES, SAID GROOVE BEING OF SUFFICIENT WIDTH AND DEPTH TO ACCOMMODATE SAID TUBE UPON COMPRESSION THEREOF AND BEING SPACED FROM SAID SUPPORT MEMBER AN AMOUNT SUFFICIENT TO PREVENT ENGAGEMENT OF SAID SUPPORT MEMBERS WITH SAID TUBE UPON COMPRESSION THEREOF. 